The operation of MPUPF can be described using a module diagram. All the modules
in the diagram are explained in the next sections.
BLOCK
Level
detector 1
ALARM
OPERATE
Blocking
logic
START
t
Timer1
DISABLE
t
Timer2
Power
factor
calculation
Level
detector 2
I3P
I_A
I_B
U3P
U_A
U_B
U_C
I_C
Figure 603: Functional module diagram
Power factor calculation
This module calculates three phase power factor using phase currents and voltages.
The three-phase power is calculated from the fundamental frequency components
(DFT) of the phase-to-earth voltages and phase-to-earth currents.
S U I U I U I
A A B B C C
= ⋅ + ⋅ + ⋅
* * *
Figure 604: Equation
Figure 605: Equation
Figure 606: Equation
Figure 607
shows the resulting sign of the power factor. This should be consistent
with the settings in the power and energy metering function of the relay.
Protection functions
1MRS759142 F
1080 REX640
Technical Manual
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